3-(4-Piperidinyl)indoles and 3-(4-Piperidinyl)pyrrolo[2,3-b]pyridines as Ligands for the ORL-1 Receptor.

A novel series of indoles and 1H-pyrrolo[2,3-b]pyridines having a piperidine ring at the 3-position were synthesized and found to bind with high affinity to the ORL-1 receptor. Structure-activity relationships at the piperidine nitrogen were investigated in each series. Substitution on the phenyl ring and nitrogen atom of the indole and 1H-pyrrolo[2,3-b]pyridine cores generated several selective high-affinity ligands that were agonists of the ORL-1 receptor.